All writing is a work of speculation. Poetry asks the reader to follow leaps of language to create a picture of something that may or may not exist. Fiction puts people who may or may not exist into situations to see how they react. Even creative nonfiction is a series of choices, with what is left out often being as important as what’s left in.
Truly speculative writing goes a few steps further, asking about situations that are otherwise impossible. Places no human being has ever been or could ever be. People, animals, even inanimate objects with extraordinary abilities. Normally, speculative fiction is the umbrella term for fantasy, horror, and science fiction, but there are dozens of sub-genres within those broad categories — the Venn diagram of speculative writing looks like something created with a Spirograph (remember those?).
I guess what we’re saying is that we’re looking for the impossible within the themes we’ve chosen. We’re looking for superheroes, monsters, the alternative past, the possible future, far-away worlds, and places in this world no one has ever been. We want neither rehashings of familiar stories, nor stories that could be portrayed in a movie with no special effects.
This is what we want: Make it magical. Make it impossible. Make it weird.